There are many cases where it is necessary to supplement liquid such as a raw material which decreases by operation or use of an equipment or apparatus. In such cases, supply of liquid such as a raw material is made by coupling a cartridge container to a container provided on the side of a main body of an equipment or apparatus for shifting the liquid between the two containers or by exchanging a container provided on the main body with another container. In a methanol fuel cell also, supplement of methanol as a fuel becomes necessary.
Various detachable types of couplers are used for simply performing such coupling or exchanging between two containers. These couplers comprise a socket having a valve and energizing means for energizing the valve in a closing direction, and a plug having a valve, energizing means for energizing the valve of the plug in a closing direction and a nozzle portion which can be detachably fitted and coupled with the socket. The plug can communicate with the socket by opening the valve of the plug and the valve of the socket when the fitted and coupled state of the socket and the plug has been completed. The valves of the plug and the socket are closed when the plug is released from the socket.
In this type of coupler, unless the coupled state between the socket and the plug is maintained accurately, leakage of liquid or other material will take place in a coupled portion of the coupler.
It has therefore been proposed to provide a mechanism which will hold the coupling state between the socket and the plug. For example, in Patent Literature 1, as shown in FIG. 11, a pair of lock arms 2 projecting on both sides of a nozzle 1 are provided in a plug P of a coupler while an engaging recesses 3 in which the lock arms 2 are received are provided in a socket S of the coupler. A coupled state can be maintained by causing projecting portions 4 of the lock arms 2 to engage with stepped portions 5 of the engaging recesses 3 by utilizing elastic deformation.
In Patent Literature 2, as shown in FIG. 12, a nozzle 6 of a plug P of a coupler for a fuel cell is formed in its foremost end portion with a peripheral groove 7 while four hooks 9 are provided in a socket S in such a manner that they project inwardly from outside of a recess 8 in which the nozzle 6 is inserted. These hooks 9 are elastic members and energized in a manner to project forwardly and, after an overriding operation of the hooks 9, the hooks 9 are engaged with the peripheral groove 7 to hold the coupled state.